1. Field of the Invention
The present invention relates to a circuit and method for determining the operating point of a semiconductor device.
2. Related Art
Semiconductor devices include numerous electronic circuits. The speed at which these electronic circuits operate is dependent on the xe2x80x9coperating pointxe2x80x9d of the semiconductor device. The operating point of a semiconductor device is dependent on the combined effect of three factors: the process variation of the semiconductor device, the temperature of the semiconductor device, and the supply voltage level for the semiconductor device.
The process variation of the semiconductor device refers to the normal variance in the structure between semiconductor devices of the same type due to variations that occur during manufacturing. Because of process variation, semiconductor devices originating from the same silicon ingot or even the same wafer often operate at different speeds. For any plurality of semiconductor devices of the same type, some devices may run at a slower than average speed, while other devices may run at a faster than average speed.
The temperature of the semiconductor device refers to its internal temperature during operation. The temperature of a semiconductor device can change while the device is operating due to heat generated within the semiconductor device or heat from external sources (e.g., power supplies).
The supply voltage of the semiconductor device refers to the voltage level of the power supply that provides power to the semiconductor device. Generally, a semiconductor device having a higher supply voltage will run faster than a device having a lower supply voltage. The supply voltage level can change while the semiconductor device is operating. For example, the supply voltage of a battery-powered device may decrease as the battery loses charge. The supply voltage can also be different if the semiconductor device is used in different applications. For example, some applications may use a 5V supply voltage whereas other applications may use a 3.3V supply voltage.
Since the operating point of a semiconductor device can vary, designers must account for the variation of a semiconductor device""s operating point in their designs. This is disadvantageous because then a semiconductor device may not operate to its full capabilities. For example, a semiconductor device having a digital circuit may have the ability to operate faster at a given time, yet it must be designed to operate slower to account for potential operating point variations. Similarly, a semiconductor device having an analog circuit may have the ability to consume less current at any given time, yet it must be designed to consume a higher amount of current to account for potential operating point variations.
What is needed is a circuit and a method that can determine the operating point of a semiconductor device.
The present invention overcomes the disadvantages and limitations described above by providing a circuit and method for determining the operating point of a semiconductor device.
In one embodiment of the present invention, an operating point circuit implemented in a semiconductor device is provided. The operating point circuit includes a delay element for receiving a first signal and producing a second signal, wherein a delay between the first signal and the second signal represents an operating point of the semiconductor device.
In another embodiment of the present invention, an operating point circuit implemented in a semiconductor device is provided. The operating point circuit includes signal generating means for generating a first signal, delaying means coupled to the signal generating means for delaying the first signal by an amount of time, and counting means for generating a count representing the amount of time that the first signal is delayed by the delaying means, wherein the count is used for determining an operating point of the semiconductor device, and wherein the counting means is driven by an external clock source.
In yet another embodiment of the present invention, a method for determining the operating point of a semiconductor device is provided. The method includes providing a delay element implemented in the semiconductor device, receiving a first signal at an input of the delay element, generating a second signal at an output of the delay element, and measuring a delay between a time when the first signal is received at the input of the delay element and a time when the second signal is produced at the output of the delay element, wherein the delay is measured by a counter driven by an external clock source.